At present about 50,000 tons of nuclear reaction products, necessary for further processing and burring, are accumulated in various storages of atomic power plants in the world. Nuclear reactions usually consume from 0.5% to 3.5% of the nuclear fuel, and the rest goes into waste including nuclear fission products, such as cesium and strontium, which waste cannot be terminated, but can be “infinitely” kept in special storage. According to conventionally known requirements for radioactive safety and environment protection, a long-term storage and burring of the nuclear waste is permitted only after appropriate chemical processing.
However, the modern technology of conversion, concentration, removal, and burring of radioactive waste (RW), primarily nuclear fuel remainder, satisfying the aforesaid requirements, is the least developed stage in the whole nuclear fuel cycle. The RW to be burred is typically placed into special containers. The final stage of operation with the RW is the burring of the containers in geologic formations that are considered a major protective barrier of such burring. This is because the construction materials and materials of the containers' shells, usually utilized in the burring structures, cannot provide reliable protection of the environment from penetration of “long-living” radioactive elements.
Usually, a geologic RW storage is a complicated engineering construction disposed more than 60 meters under the ground level. The storage includes a burring space with a floor. Bore pits are drilled in the floor to store containers with RW of high specific radioactivity. A distance between the bore pits must be from 10 to 50 meters to satisfy the heat-withdrawal regime from the containers to avoid a nuclear disaster.
Such geologic storage is characterized in that mining rocks of the formations are intensely affected by a powerful ionizing radiation field with high temperatures. Interaction of the radiation with the geologic rocks results in reduction of the radiation field, but also in radiation defects in the material structure of the rocks, involving energy accumulation in the radiated material and a local temperature increase. Such processes, being accumulated, may alter natural properties of the rocks surrounding the RW, cause phase transitions, lead to emission of gases, and influence the structural integrity of the storage walls.
According to ‘Short- and Medium-Term Management of Highly Radioactive Wastes in the United States’ by Arjun Makhijani: “The United States Department of Energy (DOE) is simultaneously pursuing two inappropriate geologic repository projects for disposal of highly radioactive waste: The Waste Isolation Pilot Plant (WIPP) in New Mexico, which is supposed to “solve” the problem of wastes containing high concentrations of transuranic radionuclides, such as plutonium, mainly arising from the US nuclear weapons production program.2 The Yucca Mountain repository in Nevada, which is being explored for its suitability for disposing of irradiated nuclear reactor fuel (also called spent fuel) and the high-level radioactive waste that results from the reprocessing of irradiated fuel. These two categories of waste, which often go under the single rubric of “high-level waste,” together contain over 99 percent of all the radioactivity in all nuclear waste”.
In another article, Mr. Arjun Makhijani describes alternative “Rejected High Level Waste Management Methods” (Science for Democratic Action, Volume 7, Number 3, May 1999) as follows:
TABLE 1WasteDisposalMethodDescriptionReasons for RejectionLiquidInjection of liquid wastedifficult to assess waste isolationInjection2(sometimes mixed withlack of engineered barriersgrout) into wellsmigration of contaminants throughhundreds of meters deep.soil to water, possibly rapidRockFill deep mined cavityhigh uncertainty about radionuclideMeltingwith high-level wastemigrationso that surrounding rock difficult to assess waste isolationis melted andinteraction of melted rock withencapsulates wastehost rock unknownspecific techniques not developedinapplicable to older reprocessingwaste with low heatIce SheetsDirect melting of wastemigration of icethrough ice to bedrock orformation of icebergs with wastesurface facility pusheddurability of waste containerdown through ice due tosystem unknownaccumulating snow andpathways for waste migrationiceunknownShoot itPlace waste into spacedanger of accident during launchinto Spaceor put rocket on collisionlarge volumes of waste wouldcourse with sunentail many flights resulting inhigher risks and higher costsreduction of volume to disposeonly long-lived radionuclidesrequires separation technologies,which pose serious environmentaland non-proliferation risksSource: Office of Technology Assessment 1985. Managing the Nation's Commercial High-Level Radioactive Waste. Washington, DC: U.S. Congress, Office of Technology Assessment, OTA-O-171, March 1985
As the above table shows, the mentioned alternative ways of utilization of the radioactive waste have significant drawbacks. Nowadays, the industry is still looking for reliable and effective ways for processing the RW.